Several studies have recorded a lower than expected cancer risk among the psychiatrically ill. A biochemical effect, either from the illness or drugs used for treatment, has been suggested as the cause. After review of existing evidence the present investigators hypothesize that relatively low reported mortality due to cancer in psychiatric groups may result (1) from statistical artifacts in the data, including failure to take into account competing risks from other causes of death, incorrect designations of cause of death, faulty diagnoses, both of cancer and of mental illness, biases in the population of patients admitted, and length of stay in hospital; and (2) if the reduced mortality rates are indeed correct, from effects of institutionalization in reducing known environmental hazards and increasing known protective influences. Possible analysis is being explored of mortality causes in VA records of WW II veterans discharged or hospitalized with mental disease. Length of hospitalization effect is confounded with mortality in such a way that in the VA group they cannot be separated. Relation of VA hospital stay to cancer mortality will therefore be investigated. Since the VA hospital stays form a lower bound on all hospitalizations, the relation found will be conservative.